1. Field of the Invention
The present invention relates to a metal terminal to be inserted into a through hole of a through-hole type electronic element such as a through-hole type capacitor, and relates to an electronic component such as a through-hole type LC filter having such a metal terminal.
2. Description of the Related Art
In the past, a metal terminal 5 which is arranged in a through-hole type capacitor 1 in a through-hole type LC filter in FIG. 4 has a structure as shown in FIGS. 5A and 5B. The through-hole type LC filter shown in FIG. 4 is composed of a through-hole type capacitor 1, ferrite beads 2 arranged on both sides of the capacitor 1, conductive metal caps 3 attached to the end portion of each of the ferrite beads 2 and a metal terminal 5 inserted into the central portion of the capacitor 1, the beads 2 and the caps 3.
The metal terminal 5 is made by forming a metal plate 5' having an unfolded shape shown in FIG. 5A into a nearly cylindrical shape shown in FIG. 5B and such that the terminal 5 has at its central portion a tongue-like part 6 protruding in an expanded condition. The metal terminal 5 secures the capacitor 1 in the through-hole type LC filter and is electrically connected to an internal electrode of the capacitor 5 in such a way that the tongue-like part 6 is inserted into the through hole of the capacitor 1 and is arranged to elastically press against the inner wall of the through hole.
However, the metal terminal 5 is relatively easily deformed if it is relatively thin, and when the terminal 5 is pushed into the through hole of the capacitor 1, the centerline L.sub.1 of the metal terminal 5 is displaced with respect to the centerline L.sub.2 of the capacitor 1 such that the centerline L.sub.2 is tilted with respect to the centerline L.sub.1. This condition causes the capacitor to be inclined. Also, the tongue-like part 6 may also be deformed in the axial direction and displaced from the centerline L.sub.3 of the length direction of the filter assembly. Such a deformed tongue-like part 6 causes large misalignments d.sub.1 and d.sub.2 between the outer surfaces of the capacitor 1 and the metal caps 3, as well as causing soldering defects when such a through-hole type LC filter is mounted on a printed circuit board or other substrate.
In the above-described LC filter, the component of inductance produced by the tongue-like part 6 is too large to ignore and the high-frequency characteristic is degraded. Furthermore, because the diameter D of the portion to be inserted into the through-hole of the ferrite beads 2 is difficult to reduce, there is a limit as to how much the thickness of the ferrite beads can be increased. This relationship prevents improvement in the elimination of noise by increasing inductance of the ferrite beads.